BOSTON AUDIO SOCIETY
February 2008 Meeting
Date: Sunday, February 17, 2008
Time: 6:00 PM
Place: Boston University, Life Science & Engineering Bldg, 24 Cummington
St, 1st Floor Conference Room (room 103), Boston, MA 02215, (617) 271-6588
Featured Guest: Joseph DeMarinis, Winchester
Topic: Techniques for Speaker Measurements
The BAS talk will consist of a PowerPoint presentation
using a DLP projector. It will give a photographic overview of my lab and
the equipment, describe the measurement techniques and show some of the
Part 2 will explain some of the techniques & limitations
of converting an audio signal into a spectrum display, using a Fast Fourier
Transform (FFT). I will compare results from Pulse and White Noise sources.
I will also discuss how using a pulse window can eliminate room reflections
from a measurement, and the limitations of that technique.
For Part 3, I have two "Live" Excel macro
demonstrations of the inner mechanism of how a Fourier Transform works.
It is an attempt to show, in a simple and visual way, something that is
generally poorly understood.
Born and raised in New York City, I graduated 1956 from Manhattan College
with a degree in Electrical Engineering. While in college, I earned money
by running my own TV repair business. For the next 25 years I worked for
the Consumer Electronics Division of Sylvania in Batavia, NY, starting as
a TV design engineer and ending as Chief Engineer of the Division. During
part of that tenure I was manager of Audio Engineering. Audio has always
been an intense interest, since the days that the word "HiFi"
was first coined. Amateur Radio was also an intense interest in those days.
When Sylvania collapsed, I joined Sylvania's parent
company, GTE, moved to Boston and worked closely with GTE Labs on a project
to investigate the prospects of Home Terminals as part of the telephone
business. That project was short-lived and I joined Digital Equipment Corporation
as a senior manager in the small systems group, where I worked on Terminals
and Personal Computers. Part of that was to help DEC get set up with measurement
sites & the skills necessary to comply with the "new" FCC
RF emissions regulations. One result of the research I did there, was to
publish several papers in the IEEE journal on Electromagnetic Compatibility.
That got me a seat on the IEEE EMC Standards Committee.
DEC eventually collapsed and I went to Polaroid as a
senior manager in their Digital Imaging group. There, I worked on digital
cameras and a variety of high-resolution digital film printers. At that
time our Country's HDTV system was being developed and I was granted a seat
on the IEEE Consumer Electronics committee on standards & testing. I
participated as an "expert observer" in some of that testing in
the Washington DC area. At Polaroid I had my own lab, equipped for Colorimetry,
CRT technology, optics, FCC compliance and other technologies.
Eventually Polaroid too, collapsed. By then I was well
past the normal retirement age and retired. But before leaving, I was able
to buy most of the equipment in my lab at essentially scrap prices. That
gave birth to www.WinchesterLab.com
on the third floor of my home. Most of what I do there is audio measurements
on microphones & speakers and whatever puttering arouses my interest.
Having worked for three companies that failed, I doubt
that anyone would want to hire me now!